1. Field of the Invention
The present invention relates to a limited slip differential, and particularly to a limited slip differential for limiting differential rotation between right and left axles by means of producing frictional resistance between a differential casing and the axles.
2. Description of the Related Art
It has been proposed previously to form a limited slip differential in which a frictionally connecting means connects a differential casing and an axle, and due to the frictional resistance which is generated between the differential casing and the axle by way of the frictionally connecting means, differential rotation between the right and left axles is limited by the degree of frictional resistance.
A limited slip differential of the type described above, is one in which the frictionally connecting means are in the form of clutch plates alternately placed between a differential casing and a side gear which is mounted on an axle and is able to move in only the axial direction thereof. The clutch plates are forced against one another to obtain frictional resistance. Another limited slip differential of the type described above is one in which the frictionally connecting means are in the form of a torque transmitting member which moves with respect to an axle in only the axial direction thereof. The torque transmitting member is forced directly against the differential casing thereby obtaining frictional resistance.
A limited slip differential of this type has been disclosed in, for example, Japanese Patent Publication No. 18726/1966. The limited slip differential disclosed in Patent Publication No. 18726/1966 comprises a side gear loosely mounted on axles and engaging with a pinion gear; a first cam portion formed on the back of the side gear so as to protrude therefrom; a driving member spline-connected to the axles and which may move in only the axial direction of the axles; a second cam portion protruding from the driving member so as to engage with the first cam portion; and clutch plates functioning as frictionally connecting means and positioned between the driving member and the differential casing.
With the limited slip differential described above, the driving member is moved axially by means of a thrust force generated between the first and second cam portions which is produced by relative rotation between the side gear and the driving member. Due to the axial movement of the driving member, the clutch plates disposed between the driving member and the differential casing are forced against one another, whereby differential rotation between the right and left axles is limited.
In the limited slip differential described above, however, the side gear is not positively centered on the differential casing, but the centering is effected only because the side gear is mounted on the pinion gear. For this reason, there has been a problem in that centering of the side gear relative to the differential housing easily gets out of order so that reliability of this limited slip differential is poor.